Question: What is the star with the highest proper motion whose companion of is Alpha Centauri B ?
Paraphrase: What companion star of Alpha Centauri B travels at the highest rate of proper motion?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q523 . ?ent wdt:P2215 ?obj . ?ent wdt:P399 wd:Q1052548 } ORDER BY DESC(?obj)LIMIT 5 
Answer: Alpha Centauri A, Alpha Centauri A